In a multi-processor computer system, a processor may access various memory devices in a number of ways ranging from local memory access via a common bus to foreign memory access via other devices, including other processors. For example, in a symmetric multi-processing (SMP) architecture, processors may directly access all memory devices. However, as the number of processors in a computer system increases, providing an adequate bandwidth for symmetric interconnection between processors and memory devices becomes more and more difficult.
In a non-uniform memory access (NUMA) system, requirements to the bandwidth between processors and memory devices are typically alleviated by connecting each processor directly to some memory devices, while providing the processor with indirect connections (e.g., via other processors) to some other memory devices. Hence, in some situations, NUMA systems may perform better than SMP systems since the aggregate memory access bandwidth usually increases as more nodes are added to the NUMA system, while in the SMP architecture the common bus interconnecting processors and memory devices may become a performance bottleneck.